Filter connectors are commonly provided with pi filters for the contacts. One pi filter design includes a pair of planar capacitors with holes through which each contact passes and a ferrite bead lying between the planar capacitors and having holes through which the contacts pass. Each planar capacitor has a terminal that must engage a location on the contact in a good electrical connection therewith. One approach is to join each contact location to a planar capacitor by soldering. The soldering is accomplished using solder pre-forms, and by re-flowing through a vapor phase oven. The soldering process is inconsistent and difficult to control due to oven variations and process fluctuations, resulting in high failure rates due to the rigid solder joint construction. Also, failures occur due to different CTE (Coefficient of Thermal Expansion) values of the different materials, resulting in high stresses when the connector is subjected to large temperature changes. Joints for electrically connecting locations along pin contacts to planar capacitors of a filter connector, which resulted in reliable positioning of the contacts and reliable electrical connections between locations along the contacts and the planar capacitors, in a design that enabled easy connection with low cost available components, would be of value.
In accordance with one embodiment of the present invention, a filter connector is provided, of the type that includes contacts lying within a shell, a pair of planar capacitors within the shell and a plurality of ferrite beads through which the contacts extend. The connector has elements that connect locations along each contact to each planar capacitor in a construction that results in reliable mechanical and electrical connections using low cost and readily available parts that allow disconnection of a single contact, and that allow easy assembly of the parts. Each contact has opposite front and rear portions and a middle portion between them, each middle portion extending through a ferrite bead and through the capacitors. Each contact rear portion has a part of larger diameter than the middle portion to form a forwardly-facing shoulder. A coil spring extending around the middle portion, has one end pressing against the contact shoulder and an opposite end pressing against a conductive layer extending around the hole of the rear planar capacitor. Another location along the contact is connected by a sliding retainer ring to a conductive layer extending around the front capacitor. The sliding ring is slid forwardly along the middle portion until it compresses the coil spring, and then locks the contact in position. The coil spring and retainer ring each provide an electrical and mechanical connection, the coil spring taking up any differential thermal expansion.
The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.